XMATCH

[m2ym]

We need to consider the following case:

(defstruct btree)
(defstruct (leaf (:include btree))
  value)
(defstruct (node (:include btree))
  left right)
(xmatch (the btree (make-node :left (make-leaf :value 1)
                              :right (make-leaf :value 2)))
  ...)

The problem is that we can't determine the lower bounds of btree should included or excluded. Maybe we will need some extension of type specifier.

[m2ym]

We don't need to care about algebraic data types on optima side. Just derive a variant type on the definition side.

[m2ym]

MULTIPLE-VALUE-XMATCH

[m2ym]

Wontfix